BRITISH AVONIAN CONODONT FAUNAS 219 
Platform 
Corina 
Posterior Anterior 
Posterior Anterior 
Blade 
Aboral edge ks 
Lateral view 
Fic. 44. Scaphignathus sp. showing morphological terms used in the text. 
Scaphignathus ? sp. B 
Plate 2, figs. 12a—c 
MATERIAL. 3 specimens: figured, X 533. 
RANGE. North Crop ZL 9-ZL to, Avon Gorge Z 12. 
DEscRIPTION. The only specimens present in our faunas have the posterior part 
of the platform missing. The blade consists of 5 denticles of equal height, situated 
on the right side of the platform when viewed from the posterior. The outer 
platform ornament consists of low transverse ridges, giving a crenulate platform, 
uniting with the inner side immediately posterior to the outer anterior blade, and 
running as a low, non-denticulate inner blade not quite to the anterior of the unit. 
It is separated from the outer lateral blade by a sulcus, which deepens anteriorly. 
In aboral view the cavity is large and asymmetrical, being expanded on the inner 
side. The unit is sub-triangular in cross-section and essentially boat-like. 
REMARKS. The presence of a median carina precludes the placing of these two 
species in either Cavusgnathus or Clydagnathus and the basal cavity differs greatly 
from the small basal cavity of Mestognathus. Scaphignathus has a small pit in adult 
specimens but a large one in juveniles. Our specimens would appear to be adult but 
are tentatively assigned to that genus. 
Genus SIPHONODELLA Branson & Mehl 
1934 Siphonognathus Branson & Mehl: 295 (non Richardson 1858). 
1944 Siphonodella nom. nov. Branson & Mehl: 245. 
TYPE SPECIES. Siphonognathus duplicata Branson & Mehl 1934. 
